GeneralAire 1042LH bypass humidifier to Ecobee 3.

Thanks to everyone for the detailed advice - I have read it all carefully and tried multiple suggestions but must be one small step from getting this to work. Hoping someone can point me in the right direction?

I have a GeneralAire Bypass Humidifier (1042LH) that I am trying to get running with my EcoBee 3. Worked fine hooked up to the old Humidistat which I have now bypassed. I tried to upload a wiring diagram but could not get it to work so I will quickly explain:

From the solenoid two identical black wires. One now runs to ACC+ on the ecobee and one to a terminal on a transformer before the furnace board. There is a second wire running to the other port on the transformer that runs to behind the ecobee but which I currently do not have attached to anything. From the transformer, one white wire runs to the HUM-N terminal on the furnace board a black wire runs to the EAC-N terminal. These connections from the transformer to the board were in place from when it was wired to the humidistat and I have not changed them.

Hi Pete
Thanks for the reply. Yes I actually went as far as to print out that diagram from your very first post before I asked my question. I made my changes based on that however .... the transformer threw me. To be clear you are saying just disconnect that, unplug both wires from the furnace board and set it aside, then simply hook that second humidifier wire to C? That simple?
Thanks again
Chris

The reason for the transformer was that the HUM terminal on your furnace board is 120v. The transformer supplied switched 24vac to the humidistat and the humidifier. Now... the ecobee supplies that switched 24vac.

I should have added to my original post that I am using the PEK - which one of your posts below suggests will not support the humidifier connection. My bad for not spotting that before. Problem I now have is that I connected the other humidifier wire to C to try it and the ecobee briefly came on and has now gone black. I took the wire out again and rechecked everything was sat as before but no dice, ecobee is still black. Did I fry it? Not sure how I would have given the humidifier wire does not carry any power. Maybe I fried the PEK?

Since I have an extra wire behind the ecobee (1 was freed up from bypassing the humidistat that had two wires originally - so I now have 5 in total) could I reconfigure this to not require the PEK anyway or is the C wire different from the others since it is carry voltage?

Chris

Last edited by fossie_chris; 02-27-18 at 06:41 PM.
Reason: Corrections

Do you have a voltmeter ?
Check for 24vac at the R and C terminals on the furnace. You may have blown a control fuse on the furnace board. It will be a small plastic fuse. Usually 3-5A and look like a plastic automotive fuse.

The R is 24vac. If it was DC.... it would be the positive and the common is the negative. Only the thermostat electronics use the C connection. All the other functions are switched to R.

Yes in total I have six wires. Bypassing the old humidistat bought me two wires that run down to the furnace board already but are no longer used. One would have to go to ACC+ but it sounds like I could now repurpose the other one to be a C wire?

First off major thanks - 1 50c 3A fuse later and everything is back up and running again! Letting the house warm up overnight and then I will try repurposing that C wire and seeing if the humidifier finally starts up.

Hmm, so it doesn't like something about connecting the wire from the humidifier to the C terminal of the furnace board. I have now removed the PEK and repurposed a wire to be the C wire from the ecobee to the furnace. That all works great until I add in the humidifier wire to that C terminal. When I do that the ecobee starts up but reboots as soon as it gets to the home screen. It does that in an infinite loop. Removing the humidifier wire from C fixes the issue. Everything is now wired exactly as in your diagram. I'm stuck again.

Ok.... try this for me..... connect the humidifier directly to the furnace board. Connect one solenoid wire to C and the other temporarily to R. The humidifier should begin and run. No call for heat is needed.

Thanks Pete. Since it keeps blowing the fuse, is there a way to test the humidifier without connecting it to the furnace board? I am thinking I should now be looking at replacing the wire from the solenoid or perhaps even the solenoid itself? The humidifier is quite simple so can't imagine what else to look at?
Chris

OK, I have an ohmmeter (finally) but little idea how to use one ... you said disconnect the wires at the solenoid. Am I then positioning one of the rods at each end of the wire to measure for whether resistance is passing through the wire properly? How would I check the solenoid (where would I make my connection points?)
Thanks